Sleep disordered breathing (SDB), described by the frequency of apnea and hypopnea events during sleep, is widely recognized as a highly prevalent but under-diagnosed condition that has a significant role in hypertension, cardiovascular and cerebrovascular disease, impaired cognitive function, hypersomnolence, decrements in daytime functioning and premature all-cause and cardiovascular mortality. Population studies over the 20 years have established the high prevalence of SDB and begun to identify the correlates and outcomes of SDB, but critical questions must be addressed to craft clinical and public health policy regarding the prevention and treatment of SDB. Important period effects that will change the SDB burden are occurring in the US, including aging of the large post World War II birth cohort, enhanced survival of older adults who have had different exposures during midlife to SDB risk factors, and an obesity epidemic. Data to address the public health burden of SDB under these new conditions are lacking. The research proposed here is designed to address the gap in understanding the burden of untreated SDB. With a 5-year continuation of the Wisconsin Sleep Cohort Study, a longitudinal study of SDB and other sleep disorders, we will continue to follow a community sample (n= 1522) of men and women, 30-60 years of age at baseline, who will have aged to 55-85 years over the continuation. With data spanning up to 25 years, with individual trajectories of data on SDB and other factors from middle to older age, we will optimally estimate the role of untreated SDB in preclinical and clinically evident cardiovascular and cerebrovascular disease (CVD/stroke), cognitive impairment, and chronic daytime dysfunction. We will also investigate the impact of age-related risk factors on sleep disorders. To achieve these goals, we will conduct follow-up protocols with overnight polysomnography, state of the art body habitus measures including DXA, echocardiography and vascular imaging, neuropsychologic test batteries, and other tests to extend our rich data on SDB status, risk factors, and outcomes. PUBLIC HEALTH RELEVANCE: The finding from the proposed longitudinal Wisconsin Sleep Cohort Study on the occurrence and progression of SDB, in a population transitioning from late middle to older age, and on the role SDB has in the development of morbidity and mortality will contribute needed new knowledge of public health significance. The findings will inform clinical decision making regarding what level of severity of SDB should be identified, whether subgroups should be targeted for case-finding, and decrease inequities due to referral and treatment based on incorrect SDB patient stereotypes. The findings will also inform public health policy regarding needed new resources, public programs designed to set goals to increase awareness of SDB, and to prevent SDB occurrence and progression, and to include SDB in federal health promotion and monitoring programs.